The long-range goal of our research is the application of multidisciplinary approaches to the elucidation on the molecular level of the steroid endocrine processes concerned with human development and reproduction and utilization of the results for the solution of biomedical and clinical problems. Our major concern is steroid hormone molecules, and the enzyme systems related to their biosynthesis. The investigations include the mechanism of estrogen and androgen biosynthesis, steroid hydroxylase and lyase reaction mechanisms, isolation, and characterization of estrogen synthetase and their multi-components, immunochemistry of aromatizing systems, identification of the courses of aromatase and other steroid biogenetic activities during fetal development in comparison with postnatal stages, the conformation of steroids in solid and solution, the competitive and noncompetitive inhibitors of hormone biosynthesis, steroid metabolism, and development of clinical assay methods. The methods involve synthesis of steroids with and without deuterium, tritium, carbon-13, carbon-14 and oxygen-18 labels at stereoselective and/or regiospecific positions, conformational analysis by neutron and X-ray crystallography and spectroscopy, chemical and biochemical distribution analysis of isotopes, incubations with various enzyme preparations, enzyme solubilization and purification, antibody production, and physicochemical and immunochemical technology.